Component({
  properties: {
    width: {
      type: String,
      value: "75vw",
    },
    height: {
      type: String,
      value: "95vh",
    },
    background: {
      type: String,
      value: "#fff",
    },
  },

  data: {
    canvasName: "signCanvas",
    ctx: "", // 上下文实例
    canvas: "", // 画布实例
    canvasWidth: 0,
    canvasHeight: 0,
    transparent: 1, // 透明度
    lineColor: "#1A1A1A", // 颜色
    lineSize: 1.5, // 笔记倍数
    lineMin: 0.5, // 最小笔画半径
    lineMax: 4, // 最大笔画半径
    pressure: 1, // 默认压力
    smoothness: 60, //顺滑度，用60的距离来计算速度
    currentPoint: {},
    currentLine: [], // 当前线条
    firstTouch: true, // 第一次触发
    radius: 1, //画圆的半径
    cutArea: { top: 0, right: 0, bottom: 0, left: 0 }, //裁剪区域
    bethelPoint: [], //保存所有线条 生成的贝塞尔点；
    lastPoint: 0,
    chirography: [], //笔迹
    currentChirography: {}, //当前笔迹
    linePrack: [], //划线轨迹 , 生成线条的实际点
    isDraw: false, // 判断用户是否绘制
    upPageNumber: 0,
    offCanvas: "",
    offCtx: "",
    dpr: "",
  },

  lifetimes: {
    attached() {
      this.data.dpr = wx.getSystemInfoSync().pixelRatio;
      const query = wx.createSelectorQuery().in(this);
      query
        .select(".canvas-sign")
        .boundingClientRect((rect) => {
          this.data.canvasWidth = rect.width * this.data.dpr;
          this.data.canvasHeight = rect.height * this.data.dpr;
        })
        .exec();
      const query1 = wx.createSelectorQuery().in(this);
      query1
        .select("#signCanvas")
        .fields({ node: true, size: true })
        .exec((res) => {
          const canvas = res[0].node;
          this.data.ctx = canvas.getContext("2d");
          canvas.width = this.data.canvasWidth;
          canvas.height = this.data.canvasHeight;
          /* 将canvas背景设置为 白底，不设置  导出的canvas的背景为透明 */
          // console.log(this, 'hahah');
          this.data.canvas = canvas;

          this.data.ctx.scale(this.data.dpr, this.data.dpr);
          this.setCanvasBg(this.data.background);
        });
      const query2 = wx.createSelectorQuery().in(this);
      query2
        .select("#offCanvas")
        .fields({ node: true, size: true })
        .exec((res) => {
          const canvas = res[0].node;
          const ctx = canvas.getContext("2d");
          canvas.width = this.data.canvasHeight;
          canvas.height = this.data.canvasWidth;
          this.data.offCanvas = canvas;
          this.data.offCtx = ctx;
          this.data.offCtx.scale(this.data.dpr, this.data.dpr);
        });
    },
  },

  methods: {
    //画两点之间的线条；参数为:line，会绘制最近的开始的两个点；
    pointToLine(line) {
      this.calcBethelLine(line);
      return;
    },
    // 笔迹开始
    uploadScaleStart(e) {
      if (e.type != "touchstart") return false;
      let ctx = this.data.ctx;
      ctx.fillStyle = this.data.lineColor; // 初始线条设置颜色
      ctx.globalAlpha = this.data.transparent; // 设置半透明
      let currentPoint = {
        x: e.touches[0].x,
        y: e.touches[0].y,
      };
      let currentLine = this.data.currentLine;
      currentLine.unshift({
        time: new Date().getTime(),
        dis: 0,
        x: currentPoint.x,
        y: currentPoint.y,
      });
      this.setData({
        currentPoint,
      });
      if (this.data.firstTouch) {
        this.setData({
          cutArea: {
            top: currentPoint.y,
            right: currentPoint.x,
            bottom: currentPoint.y,
            left: currentPoint.x,
          },
          firstTouch: false,
        });
      }
      this.pointToLine(currentLine);
    },
    // 笔迹移动
    uploadScaleMove(e) {
      if (e.type != "touchmove") return false;
      if (e.cancelable) {
        // 判断默认行为是否已经被禁用
        if (!e.defaultPrevented) {
          e.preventDefault();
        }
      }
      let point = {
        x: e.touches[0].x,
        y: e.touches[0].y,
      };

      //测试裁剪
      if (point.y < this.data.cutArea.top) {
        this.data.cutArea.top = point.y;
      }
      if (point.y < 0) this.data.cutArea.top = 0;

      if (point.x > this.data.cutArea.right) {
        this.data.cutArea.right = point.x;
      }
      if (this.data.canvasWidth - point.x <= 0) {
        this.data.cutArea.right = this.data.canvasWidth;
      }
      if (point.y > this.data.cutArea.bottom) {
        this.data.cutArea.bottom = point.y;
      }
      if (this.data.canvasHeight - point.y <= 0) {
        this.data.cutArea.bottom = this.data.canvasHeight;
      }
      if (point.x < this.data.cutArea.left) {
        this.data.cutArea.left = point.x;
      }
      if (point.x < 0) this.data.cutArea.left = 0;

      this.setData({
        lastPoint: this.data.currentPoint,
        currentPoint: point,
      });
      let currentLine = this.data.currentLine;
      currentLine.unshift({
        time: new Date().getTime(),
        dis: this.distance(this.data.currentPoint, this.data.lastPoint),
        x: point.x,
        y: point.y,
      });
      this.pointToLine(currentLine);
    },
    // 笔迹结束
    uploadScaleEnd(e) {
      if (e.type != "touchend") return 0;
      let point = {
        x: e.changedTouches[0].x,
        y: e.changedTouches[0].y,
      };
      this.setData({
        lastPoint: this.data.currentPoint,
        currentPoint: point,
      });
      let currentLine = this.data.currentLine;
      currentLine.unshift({
        time: new Date().getTime(),
        dis: this.distance(this.data.currentPoint, this.data.lastPoint),
        x: point.x,
        y: point.y,
      });
      if (currentLine.length > 2) {
        var info =
          (currentLine[0].time - currentLine[currentLine.length - 1].time) /
          currentLine.length;
      }
      //一笔结束，保存笔迹的坐标点，清空，当前笔迹
      //增加判断是否在手写区域；
      this.pointToLine(currentLine);
      var currentChirography = {
        lineSize: this.data.lineSize,
        lineColor: this.data.lineColor,
      };
      var chirography = this.data.chirography;
      chirography.unshift(currentChirography);
      this.setData({
        chirography,
      });
      var linePrack = this.data.linePrack;
      linePrack.unshift(this.data.currentLine);
      this.setData({
        linePrack,
        currentLine: [],
      });
      this.data.isDraw = true;
    },

    //计算插值的方式；
    calcBethelLine(line) {
      if (line.length <= 1) {
        line[0].r = this.data.radius;
        return;
      }
      let x0,
        x1,
        x2,
        y0,
        y1,
        y2,
        r0,
        r1,
        r2,
        len,
        lastRadius,
        dis = 0,
        time = 0,
        curveValue = 0.5;
      if (line.length <= 2) {
        x0 = line[1].x;
        y0 = line[1].y;
        x2 = line[1].x + (line[0].x - line[1].x) * curveValue;
        y2 = line[1].y + (line[0].y - line[1].y) * curveValue;
        x1 = x0 + (x2 - x0) * curveValue;
        y1 = y0 + (y2 - y0) * curveValue;
      } else {
        x0 = line[2].x + (line[1].x - line[2].x) * curveValue;
        y0 = line[2].y + (line[1].y - line[2].y) * curveValue;
        x1 = line[1].x;
        y1 = line[1].y;
        x2 = x1 + (line[0].x - x1) * curveValue;
        y2 = y1 + (line[0].y - y1) * curveValue;
      }
      //从计算公式看，三个点分别是(x0,y0),(x1,y1),(x2,y2) ；(x1,y1)这个是控制点，控制点不会落在曲线上；实际上，这个点还会手写获取的实际点，却落在曲线上
      len = this.distance({ x: x2, y: y2 }, { x: x0, y: y0 });
      lastRadius = this.data.radius;
      for (let n = 0; n < line.length - 1; n++) {
        dis += line[n].dis;
        time += line[n].time - line[n + 1].time;
        if (dis > this.data.smoothness) break;
      }
      this.setData({
        radius:
          Math.min(
            (time / len) * this.data.pressure + this.data.lineMin,
            this.data.lineMax
          ) * this.data.lineSize,
      });
      line[0].r = this.data.radius;
      //计算笔迹半径；
      if (line.length <= 2) {
        r0 = (lastRadius + this.data.radius) / 2;
        r1 = r0;
        r2 = r1;
        //return;
      } else {
        r0 = (line[2].r + line[1].r) / 2;
        r1 = line[1].r;
        r2 = (line[1].r + line[0].r) / 2;
      }
      let n = 5;
      let point = [];
      for (let i = 0; i < n; i++) {
        let t = i / (n - 1);
        let x = (1 - t) * (1 - t) * x0 + 2 * t * (1 - t) * x1 + t * t * x2;
        let y = (1 - t) * (1 - t) * y0 + 2 * t * (1 - t) * y1 + t * t * y2;
        let r = lastRadius + ((this.data.radius - lastRadius) / n) * i;
        point.push({ x: x, y: y, r: r });
        if (point.length == 3) {
          let a = this.ctaCalc(
            point[0].x,
            point[0].y,
            point[0].r,
            point[1].x,
            point[1].y,
            point[1].r,
            point[2].x,
            point[2].y,
            point[2].r
          );
          a[0].color = this.data.lineColor;
          this.bethelDraw(a, 1);
          point = [{ x: x, y: y, r: r }];
        }
      }
      this.setData({
        currentLine: line,
      });
    },
    //求两点之间距离
    distance(a, b) {
      let x = b.x - a.x;
      let y = b.y - a.y;
      return Math.sqrt(x * x + y * y);
    },
    ctaCalc(x0, y0, r0, x1, y1, r1, x2, y2, r2) {
      let a = [],
        vx01,
        vy01,
        norm,
        n_x0,
        n_y0,
        vx21,
        vy21,
        n_x2,
        n_y2;
      vx01 = x1 - x0;
      vy01 = y1 - y0;
      norm = Math.sqrt(vx01 * vx01 + vy01 * vy01 + 0.0001) * 2;
      vx01 = (vx01 / norm) * r0;
      vy01 = (vy01 / norm) * r0;
      n_x0 = vy01;
      n_y0 = -vx01;
      vx21 = x1 - x2;
      vy21 = y1 - y2;
      norm = Math.sqrt(vx21 * vx21 + vy21 * vy21 + 0.0001) * 2;
      vx21 = (vx21 / norm) * r2;
      vy21 = (vy21 / norm) * r2;
      n_x2 = -vy21;
      n_y2 = vx21;
      a.push({ mx: x0 + n_x0, my: y0 + n_y0, color: "#1A1A1A" });
      a.push({
        c1x: x1 + n_x0,
        c1y: y1 + n_y0,
        c2x: x1 + n_x2,
        c2y: y1 + n_y2,
        ex: x2 + n_x2,
        ey: y2 + n_y2,
      });
      a.push({
        c1x: x2 + n_x2 - vx21,
        c1y: y2 + n_y2 - vy21,
        c2x: x2 - n_x2 - vx21,
        c2y: y2 - n_y2 - vy21,
        ex: x2 - n_x2,
        ey: y2 - n_y2,
      });
      a.push({
        c1x: x1 - n_x2,
        c1y: y1 - n_y2,
        c2x: x1 - n_x0,
        c2y: y1 - n_y0,
        ex: x0 - n_x0,
        ey: y0 - n_y0,
      });
      a.push({
        c1x: x0 - n_x0 - vx01,
        c1y: y0 - n_y0 - vy01,
        c2x: x0 + n_x0 - vx01,
        c2y: y0 + n_y0 - vy01,
        ex: x0 + n_x0,
        ey: y0 + n_y0,
      });
      a[0].mx = a[0].mx.toFixed(1);
      a[0].mx = parseFloat(a[0].mx);
      a[0].my = a[0].my.toFixed(1);
      a[0].my = parseFloat(a[0].my);
      for (let i = 1; i < a.length; i++) {
        a[i].c1x = a[i].c1x.toFixed(1);
        a[i].c1x = parseFloat(a[i].c1x);
        a[i].c1y = a[i].c1y.toFixed(1);
        a[i].c1y = parseFloat(a[i].c1y);
        a[i].c2x = a[i].c2x.toFixed(1);
        a[i].c2x = parseFloat(a[i].c2x);
        a[i].c2y = a[i].c2y.toFixed(1);
        a[i].c2y = parseFloat(a[i].c2y);
        a[i].ex = a[i].ex.toFixed(1);
        a[i].ex = parseFloat(a[i].ex);
        a[i].ey = a[i].ey.toFixed(1);
        a[i].ey = parseFloat(a[i].ey);
      }
      return a;
    },
    bethelDraw(point, is_fill, color) {
      let ctx = this.data.ctx;
      ctx.beginPath();
      ctx.moveTo(point[0].mx, point[0].my);
      if (undefined != color) {
        ctx.fillStyle = color;
        ctx.strokeStyle = color;
      } else {
        ctx.fillStyle = point[0].color;
        ctx.strokeStyle = point[0].color;
      }
      for (let i = 1; i < point.length; i++) {
        ctx.bezierCurveTo(
          point[i].c1x,
          point[i].c1y,
          point[i].c2x,
          point[i].c2y,
          point[i].ex,
          point[i].ey
        );
      }
      ctx.stroke();
      if (undefined != is_fill) {
        ctx.fill(); //填充图形 ( 后绘制的图形会覆盖前面的图形, 绘制时注意先后顺序 )
      }
    },
    //设置canvas背景色  不设置  导出的canvas的背景为透明
    //@params：字符串  color
    setCanvasBg(color) {
      console.log("开始设置背景色");
      /* 将canvas背景设置为 白底，不设置  导出的canvas的背景为透明 */
      //rect() 参数说明  矩形路径左上角的横坐标，左上角的纵坐标, 矩形路径的宽度, 矩形路径的高度
      this.data.ctx.rect(0, 0, this.data.canvasWidth, this.data.canvasHeight);
      this.data.ctx.fillStyle = color;
      this.data.ctx.fill(); //设置填充
    },
    //上传
    async getCanvasImg() {
      if (!this.data.isDraw) {
        return false;
      }
      this.data.offCtx.rotate((-90 * Math.PI) / 180);
      const srcImg = this.data.offCanvas.createImage();
      // 等待图片加载
      await new Promise((resolve) => {
        srcImg.onload = resolve;
        srcImg.src = this.data.canvas.toDataURL("image/png", 1); // 要加载的图片 url
      });
      let width = this.data.canvasWidth / this.data.dpr;
      let height = this.data.canvasHeight / this.data.dpr;
      this.data.offCtx.drawImage(srcImg, -width, 0, width, height);
      return new Promise((resolve, reject) => {
        wx.canvasToTempFilePath({
          canvas: this.data.offCanvas,
          fileType: "png", // png默认无背景是透明的，可以改jpg
          quality: 1, //图片质量
          success: resolve,
          fail: reject,
        });
      });
    },
    clear() {
      this.data.ctx.clearRect(
        0,
        0,
        this.data.canvasWidth,
        this.data.canvasHeight
      );
      //设置canvas背景
      this.setCanvasBg(this.data.background);
      // 初始化数据
      this.data.isDraw = false;
      this.data.currentLine = [];
      this.data.currentPoint = {};
      this.data.bethelPoint = [];
      this.data.chirography = [];
      this.data.currentChirography = {};
      this.data.linePrack = [];
    },
  },
});
